1. Field of the Invention
The present invention relates to a license light for illuminating a license plate mounted to a rear fender of a two-wheel vehicle such as a motorcycle.
2. Description of Background Art
License lights of a type illuminating a license plate (number plate) mounted to a rear fender provided at a rear portion of a body of a motorcycle are known. One example of these is disclosed in Japanese Patent Laid-open No. Hei 10-86869. The license light described in this document, which is disposed under a tail light, is configured to collect light emitted from a lamp as a light source through a lens, and to obliquely illuminate the surface of the license plate with the light, from above or below.
The related art license light, however, has a problem. Since the license light collects light emitted from the lamp through the lens and obliquely illuminates the surface of the license plate with the light, the brightness distribution on the surface of the license plate is uneven. Specifically, the brightness is high at a central portion of the plate surface illuminated with the light having passed through a central portion of the lens; however, the brightness becomes lower towards the peripheral portion of the plate surface. Uneven brightness also occurs as a result of illuminating the license light with light from a tail light. Because of this uneven brightness, the related art license light fails to uniformly illuminate the entire surface of the license plate.
To cope with this problem, one approach that has been considered has been to increase the size of the surface area the lens, so that more light can pass through the center portion of the lens, and thus better illuminate the license plate. In this case, however, there is a difficulty in mounting a license light having an enlarged lens on the narrow mounting portion in a rear fender. Also, there are other limitations with having a light with an enlarged lens. These include limitations in the degree of freedom in design of an external shape, the degree of freedom in structure, the increased weight, and the mounting position. As is apparent, increasing the size of the lens fails to satisfy the above-described problem.
In view of the foregoing, the object of present invention is to provide a license light capable of uniformly illuminating the entire display plane of a license plate with light emitted from a lamp, while at the same time, reducing the size and weight, eliminating the limitation to the degree of freedom in arrangement, and simplifying the structure.
To achieve the above object, the present invention provides a license light at a rear end portion of a body of a two-wheeled vehicle, for illuminating a license plate mounted to a rear fender with light that is emitted from a lamp to the license plate through a lens. A prism is provided on one of lens planes of a portion of the lens, through which the light emitted from the lamp is directed to the license plate.
With this license light, when light emitted from the lamp is directed to the license plate through the lens, the light is scattered by the prism provided on the lens plane of the lens; and is uniformly diffused from the lens plane to the license plate. Accordingly, the display plane of the license plate can be uniformly illuminated with the light without occurrence of uneven brightness, with a result that the vehicle number can be clearly viewed.
Further the prism of the present invention is formed by arraying a plurality of prism elements, each of which is directed in a direction parallel to the center line of the vehicular body, in a direction perpendicular to the center line.
With this configuration, the light passing through the lens is effectively and uniformly diffused in the width direction of the vehicular body by the plurality of prism elements arrayed in the direction perpendicular to the center line of the vehicular body. As a result, the display surface of the license plate can be more effectively illuminated with the light, while avoiding the problem of uneven brightness.
Still further, the prism of the present invention is provided on the inside of one of the lens planes of the lens, and thus is on the side close to the lamp.
With this configuration, since the prism of the lens is not exposed on the outer side, the effect of uniformly diffusing light by the prism can be further enhanced.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.